Download or read book Dietary Overlap Between Sympatric Mexican Spotted and Great Horned Owls in Arizona written by Joseph L. Ganey and published by . This book was released on 2005 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: We estimated diet composition of sympatric Mexican spotted (Strix occidentalis lucida, n = 7 pairs of owls) and great horned owls (Bubo virginianus, n = 4 pairs) in ponderosa pine (Pinus ponderosa) - Gambel oak (Quercus gambelii) forest, northern Arizona. Both species preyed on mammals, birds, and insects; great horned owls also ate lizards. Mammals dominated the diet of both species. Mammals comprised 63 and 62% of all prey items identified in diets of spotted and great horned owls, respectively, and 94 and 95% of prey biomass. Both species primarily preyed on a few groups of small mammals. Observed overlap in diet composition between species (0.95) was greater than expected based on null models of diet overlap, and the size range of prey taken overlapped entirely. Mean prey mass was similar for both species (great horned owl, 47.0 ± 7.4 g [SE], n = 94 items; spotted owl, 40.1 ± 1.8 g, n = 1,125 items). Great horned owls consumed larger proportions of diurnally active prey than spotted owls, which primarily consumed nocturnally active mammals. Our results, coupled with a previous analysis showing that these owls foraged in the same general areas (Ganey and others 1997), suggests that they could compete for food resources, which are assumed to be limiting in at least some years. They may minimize the potential for resource competition, however, by concentrating foraging activities in different habitats (Ganey and others 1997) and by foraging at different times, when different suites of prey species are active.
Download or read book Dietary Overlap Between Sympatric Mexican Spotted and Great Horned Owls in Arizona written by Joseph L. Ganey and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Western Birds written by and published by . This book was released on 2006 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Field Guide to Owls of California and the West written by Hans J. Peeters and published by Univ of California Press. This book was released on 2007-10-09 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most owls are almost perfectly adapted to life in the dark. Their vaguely humanoid faces reflect the spectacular evolution of their hearing and vision, which has made flight, romance, and predation possible in the near absence of light. This accessible guide, full of intriguing anecdotes, covers all 19 species of owls occurring in North America. More than an identification guide, Field Guide to Owls of California and the West describes the biology and behavior of owls to make finding and identifying them easier and watching them more enjoyable. The guide also explores the conservation challenges that owls face and tells how owls provide insights to scientists working in fields from technology to health. * Color plates illustrate each species * Range maps show the western distribution of North America's owls, 14 of which occur in California * Offers tips for finding and watching owls * Gives information on how to design, place, and maintain nest boxes * Describes human attitudes toward owls through history, including in Native American cultures of the West
Download or read book Food Habits of Mexican Spotted Owls in Arizona written by Joseph L. Ganey and published by . This book was released on 1992 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Competitive Interactions and Resource Partitioning Between Northern Spotted Owls and Barred Owls in Western Oregon written by J. David Wiens and published by . This book was released on 2012 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: The federally threatened northern spotted owl (Strix occidentalis caurina) is the focus of intensive conservation efforts that have led to much forested land being reserved as habitat for the owl and associated wildlife species throughout the Pacific Northwest of the United States. Recently, however, a relatively new threat to spotted owls has emerged in the form of an invasive competitor: the congeneric barred owl (Strix varia). As barred owls have rapidly expanded their populations into the entire range of the northern spotted owl, mounting evidence indicates that they are displacing, hybridizing with, and even killing spotted owls. The barred owl invasion into western North America has made an already complex conservation issue even more contentious, and a lack of information on the ecological relationships between the 2 species has hampered conservation efforts. During 2007-2009 I investigated spatial relationships, habitat selection, diets, survival, and reproduction of sympatric spotted owls and barred owls in western Oregon, USA. My overall objective was to determine the potential for and possible consequences of competition for space, habitat, and food between the 2 species. My study included 29 spotted owls and 28 barred owls that were radio-marked in 36 neighboring territories and monitored over a 24-month tracking period. Based on repeated surveys of both species, the number of territories occupied by pairs of barred owls in the 745 km2 study area (82) greatly outnumbered those occupied by pairs of spotted owls (15). Estimates of mean size of home-ranges and core-use areas of spotted owls (1,843 ha and 305 ha, respectively) were 2-4 times larger than those of barred owls (581 ha and 188 ha, respectively). Individual spotted and barred owls in adjacent territories often had overlapping home ranges, but inter-specific space sharing was largely restricted to broader foraging areas in the home range with minimal spatial overlap among core-use areas. I used an information-theoretic approach to rank discrete choice models representing alternative hypotheses about the influence of forest conditions and interspecific interactions on species-specific patterns of nighttime habitat selection. Spotted owls spent a disproportionate amount of time foraging on steep slopes in ravines dominated by old (>120 yrs old) conifer trees. Barred owls used available forest types more evenly than spotted owls, and were most strongly associated with patches of large hardwood and conifer trees that occupied relatively flat areas along streams. Spotted and barred owls differed in the relative use of old conifer forest (higher for spotted owls) and slope conditions (steeper slopes for spotted owls). I found no evidence that the 2 species differed in their use of young, mature, and riparian-hardwood forest types, and both species avoided forest-nonforest edges. The best resource selection function for spotted owls indicated that the relative probability of a location being selected was reduced if the location was within or in close proximity to a core-use area of a barred owl. I used pellet analysis and measures of food niche overlap to examine the potential for dietary competition between spatially associated pairs of spotted owls and barred owls. I identified 1,223 prey items from 15 territories occupied by pairs of spotted owls and 4,299 prey items from 24 territories occupied by pairs of barred owls. Diets of both species were dominated by nocturnal mammals, but diets of barred owls included many terrestrial, aquatic, and diurnal prey species that were rare or absent in diets of spotted owls. Northern flying squirrels (Glaucomys sabrinus), woodrats (Neotoma fuscipes, N. cinerea), and lagomorphs (Lepus americanus, Sylvilagus bachmani) were particularly important prey for both owl species, accounting for 81% and 49% of total dietary biomass for spotted owls and barred owls, respectively. Dietary overlap between pairs of spotted and barred owls in adjacent territories ranged from 28-70% (mean = 42%) In addition to overlap in resource use, I also identified strong associations between the presence of barred owls and the behavior of spotted owls, as shown by changes in space-use, habitat selection, and reproductive output of spotted owls exposed to different levels of spatial overlap with barred owls in adjacent territories. Barred owls in my study area displayed both numeric and demographic superiority over spotted owls; the annual survival probability of radio-marked spotted owls from known-fate analyses (0.81, SE = 0.05) was lower than that of barred owls (0.92, SE = 0.04), and barred owls produced over 6 times as many young over a 3-year period as spotted owls. Survival of both species was positively associated with an increasing proportion of old (>120 yrs old) conifer forest within the home range, which suggested that availability of old forest was a potential limiting factor in the competitive relationship between the 2 species. When viewed collectively, my results support the hypothesis that interference competition with a high density of barred owls for territorial space can act to constrain the availability of critical resources required for successful recruitment and reproduction of spotted owls. My findings have broad implications for the conservation of spotted owls, as they suggest that spatial heterogeneity in survival and reproduction may arise not only because of differences among territories in the quality of forest habitat, but also because of the spatial distribution of an invasive competitor.
Download or read book Hawks Eagles Falcons of North America written by Paul A. Johnsgard and published by Washington : Smithsonian Institution Press. This book was released on 1990 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: ANIMALS
Download or read book The Eastern Screech Owl written by Frederick R. Gehlbach and published by Texas A&M University Press. This book was released on 2008 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: The eastern screech owl, widespread over the eastern half of North America and noticeably tolerant of human activity, is one of America's most familiar birds. Residing naturally in wooded environs with tree cavities, this owl lives well in suburbia and can be found nesting in mailboxes, porch columns, and purple martin houses. Based on a twenty-five-year study, biologist Frederick R. Gehlbach tells the life story of the eastern screech owl, focusing on case studies of suburban and rural study plots in Central Texas. This is the first thorough study of major life-history, behavioral, and ecological features of the species. Indeed, it is the first concurrent, comparative study of an urban and a rural population of any New World animal. Told in a personal voice, the story of these birds will interest all who have not lost touch with their ancestral world. However, Gehlbach has also included quantitative data and analysis of interest to ecologists, wildlife biologists, and ornithologists. Photographs (including color shots of the gray and rufous phases), figures, and tables provide further detail. Gehlbach's investigations have been those of not only an academic ecologist, but a suburbanite curious about his natural surroundings. The result is a model of research on species population dynamics and adaptation, yielding an emerging picture of what the eastern screech owl needs for successful coexistence with human neighbors.
Download or read book Raptor survey techniques written by Mark R. Fuller and published by . This book was released on 1987 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Neotropical Owls written by Paula L. Enriquez and published by Springer. This book was released on 2017-07-24 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a comprehensive biological and ecological information about owls in the neotropic area. In addition the book covers topics such as threats and conservation strategies for these nocturnal birds of prey from 18 Neotropical countries. Owls are a good example of diversification processes and have developed evolutionary characteristics themselves. These species are found almost everywhere in the world but most of them are distributed in tropical areas and about a third of them live in the Neotropics. This biogeographic region has a high biodiversity and even share lineages of species from other continents because at some point all were part of Pangea. Although we still have much to know and understand about this diverse, scarcely studied and threatened group this work aims to be a precedent for future and further research on the subject.
Download or read book Wildlife Habitats in Managed Forests written by Jack Ward Thomas and published by . This book was released on 1979 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: That is what this book is about. It is a framework for planning, in which habitat is the key to managing wildlife and making forest managers accountable for their actions. This book is based on the collective knowledge of one group of resource professionals and their understanding about how wildlife relate to forest habitats. And it provides a longoverdue system for considering the impacts of changes in forest structure on all resident wildlife.
Download or read book The Scientific Basis for Conserving Forest Carnivores written by Leonard F. Ruggiero and published by . This book was released on 1994 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: This cooperative effort by USDA Forest Service Research and the National Forest System assesses the state of knowledge related to the conservation status of four forest carnivores in the western United States: American marten, fisher, lynx, and wolverine. The conservation assessment reviews the biology and ecology of these species. It also discusses management considerations stemming from what is known and identifies information needed. Overall, we found huge knowledge gaps that make it difficult to evaluate the species' conservation status.
Download or read book North American Rodents written by David J. Hafner and published by IUCN. This book was released on 1998 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first comprehensive treatment of North American rodents of conservation concern. This action plan summarizes the rodent fauna of North America and provides available information on every rodent taxon that has been considered to be of conservation concern by state, provincial and private conservation agencies and regional experts. It is hoped that the survey provided in this action plan will serve as a common ground for all these parties in drawing up conservation strategies for rodents.
Download or read book Ecology written by Charles J. Krebs and published by Benjamin-Cummings Publishing Company. This book was released on 2001 with total page 695 pages. Available in PDF, EPUB and Kindle. Book excerpt: This best-selling majors ecology book continues to present ecology as a series of problems for readers to critically analyze. No other text presents analytical, quantitative, and statistical ecological information in an equally accessible style. Reflecting the way ecologists actually practice, the book emphasizes the role of experiments in testing ecological ideas and discusses many contemporary and controversial problems related to distribution and abundance. Throughout the book, Krebs thoroughly explains the application of mathematical concepts in ecology while reinforcing these concepts with research references, examples, and interesting end-of-chapter review questions. Thoroughly updated with new examples and references, the book now features a new full-color design and is accompanied by an art CD-ROM for instructors. The field package also includes The Ecology Action Guide, a guide that encourages readers to be environmentally responsible citizens, and a subscription to The Ecology Place (www.ecologyplace.com), a web site and CD-ROM that enables users to become virtual field ecologists by performing experiments such as estimating the number of mice on an imaginary island or restoring prairie land in Iowa. For college instructors and students.
Download or read book Current Ornithology Volume 17 written by Charles F. Thompson and published by Springer Science & Business Media. This book was released on 2010-09-09 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current Ornithology publishes authoritative, up-to-date, scholarly reviews of topics selected from the full range of current research in avian biology. Topics cover the spectrum from the molecular level of organization to population biology and community ecology. The series seeks especially to review (1) fields in which an abundant recent literature will benefit from synthesis and organization, or (2) newly emerging fields that are gaining recognition as the result of recent discoveries or shifts in perspective, or (3) fields in which students of vertebrates may benefit from comparisons of birds with other classes. All chapters are invited, and authors are chosen for their leadership in the subjects under review.
Download or read book Conservation by Proxy written by Tim Caro and published by Island Press. This book was released on 2010-06-23 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: The vast scope of conservation problems has forced biologists and managers to rely on "surrogate" species to serve as shortcuts to guide their decision making. These species-known by a host of different terms, including indicator, umbrella, and flagship species-act as proxies to represent larger conservation issues, such as the location of biodiversity hotspots or general ecosystem health. Synthesizing an immense body of literature, conservation biologist and field researcher Tim Caro offers systematic definitions of surrogate species concepts, explores biological theories that underlie them, considers how surrogate species are chosen, critically examines evidence for and against their utility, and makes recommendations for their continued use. The book clarifies terminology and contrasts how different terms are used in the real world considers the ecological, taxonomic, and political underpinnings of these shortcuts identifies criteria that make for good surrogate species outlines the circumstances where the application of the surrogate species concept shows promise Conservation by Proxy is a benchmark reference that provides clear definitions and common understanding of the evidence and theory behind surrogate species. It is the first book to review and bring together literature on more than fifteen types of surrogate species, enabling us to assess their role in conservation and offering guidelines on how they can be used most effectively.
Download or read book Bird Nests and Construction Behaviour written by Mike Hansell and published by Cambridge University Press. This book was released on 2000-08-31 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bird Nests and Construction Behaviour provides a broad view of our understanding of the biology of the nests, bowers and tools made by birds. It illustrates how, among vertebrates, the building abilities of birds are more impressive and consistent than for any other builders other than ourselves, yet birds seem to require no special equipment, and use quite uncomplicated behaviour. In doing so, the book raises general issues in the field of behavioural ecology including the costs of reproduction, sexual selection and the organisation and complexity of behaviour. Written for students and researchers of animal behaviour, behavioural ecology and ornithology, it will nevertheless make fascinating reading for architects and engineers interested in understanding how structures are created by animals.
